Downhole Tool Sidetrack Borehole for Virgin Formation Measurement
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Solution Overview
Problem
Conventional borehole logging tools have shallow depths of investigation, measuring only the invaded or flushed zone near the wellbore wall, which is not representative of the formation beyond the drilling damage, due to limitations in signal penetration and noise ratio, making it difficult to obtain accurate measurements in virgin formations.
Innovation Solution
A downhole tool with a miniature logging system that includes a drilling/coring module and packers to create a sidetrack borehole underbalanced drilling condition, allowing measurements to be taken beyond the invaded zone by deploying sensors in a small diameter sidetrack borehole drilled beyond the flushed zone radius, thereby avoiding mudcake formation and fines invasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional borehole logging tools are used, then measurements can be made in the flushed zone near the wellbore wall, but the measurements are limited to shallow depths (a few inches) and cannot penetrate deep into the formation beyond the invaded zone
Solution Approach 1:
The invention divides the formation evaluation into two separate access paths: the original borehole for shallow measurements and a new sidetrack borehole for deep measurements. The sidetrack borehole is drilled through the invaded zone to reach the non-invaded formation, allowing logging tools to measure deep formation properties without being limited by the shallow depth constraint of conventional tools.
Solution Approach 2:
The sidetrack borehole acts as an intermediary channel that bridges the gap between the wellbore and the deep non-invaded formation. By drilling a new hole through the invaded zone, it provides a direct pathway for logging tools to access and measure formation properties beyond the flushed zone, overcoming the depth limitation of conventional tools.
2Measurement precision
If measurements are made in the flushed zone within a few inches of the borehole wall, then logging tools can obtain signals, but the measurements reflect the invaded/damaged zone rather than the representative formation properties
Solution Approach 1:
The invention extracts the measurement function from the contaminated environment of the original borehole and relocates it to the clean, non-invaded formation through the sidetrack borehole. This separates the measurement process from the harmful effects of drilling fluid contamination and fines invasion that occur in the flushed zone.
Solution Approach 2:
The sidetrack borehole creates a new, uncontaminated pathway that copies the successful measurement capability of conventional tools while avoiding their harmful effects. It provides a fresh access route into the formation that does not suffer from the same contamination problems as the original borehole.
3Length of stationary object
If the depth of investigation is increased beyond the flushed zone, then measurements can reach non-invaded formation, but the signal to noise ratio decreases and deep reading measurements become unreliable
Solution Approach 1:
The invention changes the spatial dimension of measurement access by creating a sidetrack borehole that extends radially outward from the wellbore through the invaded zone to the non-invaded formation. This new dimensional pathway allows logging tools to reach deep formation zones without being constrained by the axial depth limitations and signal degradation problems of conventional borehole tools.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate formation evaluation measurements in non-invaded zones with deeper signal penetration and reduced contamination, providing more reliable data on fluid saturations, porosities, and permeabilities, and allowing for uncontaminated fluid sampling, improving the accuracy of reservoir characterization.
Implementation Method 1
The packers and pump module can be used to create an underbalanced drilling condition in an isolated section of the wellbore
Implementation Method 2
The drilling/coring module is used to make the sidetrack borehole
Data Source
AI summary
The present invention relates to making one or more measurements in a virgin formation using a downhole tool that includes a miniature logging tool. The downhole tool is disposed in a wellbore penetrating the formation, adjacent to the formation, and a sidetrack borehole is made into the formation. All or a portion of the miniature logging tool is deployed into the sidetrack borehole and measurements are made in the virgin formation using the miniature logging tool. The downhole tool may include a drilling/coring module, a pump module, and packers. The drilling/coring module is used to make the sidetrack borehole, and the packers and pump module can be used to create an underbalanced drilling condition in an isolated section of the wellbore.